1. Field of the Invention
The invention generally relates to a filter module having a mechanically-positionable test probe.
2. Description of the Related Art
In many cleanroom applications, filters are often required to be scan-tested for leaks after installation. This requirement is problematic when the space available downstream of the filter is limited, as positioning a probe during testing may become difficult, if not impossible, to perform. Examples of such applications where access to the downstream side of the filter is limited, but are not limited to, housings utilized in filtered exhaust applications.
For example, in a filtered exhaust application, the interstitial space defined between a housing and a filter disposed therein can often not be readily accessed by a technician. While the face of the filter is exposed to the room in which the filter is operating, the housing is disposed in the surrounding structure, such as a wall, ceiling or floor, which is essentially inaccessible from the room without breaking the pressure barrier defined by the structure. Thus, testing of the installed exhaust filter is usually performed in a reverse flow direction to facilitate scanning from the cleanroom side of the filter. This manner of testing is controversial, as many believe that some pin hole filter leaks are flow direction dependent, and as such, a filter passing a scan test with air flowing in a first direction, may leak when the flow through the filter is reversed to the direction used during operation of the cleanroom. As leaking filters may pose health hazards, allow downstream contamination, and present regulatory issues or other undesirable problems, it is highly desirable to test installed filters in the same flow direction utilized during normal filter operation.
Thus, there is a need for a filter housing having an integrated probe which can be mechanically positioned to facilitate scanned leak detection of a filter installed in the housing.